package com.wondersgroup.core.util;

/**
 * 提供经纬度相关计算方法
 * @author wanglei
 */
public class LatLonUtil {  
    
    private static final double PI = 3.14159265;  
    private static final double EARTH_RADIUS = 6378137;  
    private static final double RAD = PI / 180.0;  
  
    /** 
     * @param raidus 单位米 
     * return minLat,minLng,maxLat,maxLng 
     */  
    public static double[] getAround(double lat,double lon,int raidus){
        if(raidus <= 0){
        	return new double[]{lat,lon,lat,lon};
        }
        Double latitude = lat;  
        Double longitude = lon;  
          
        Double degree = (24901*1609)/360.0;
        double raidusMile = raidus;  
          
        Double dpmLat = 1/degree;  
        Double radiusLat = dpmLat*raidusMile;
        Double minLat = latitude - radiusLat;
        Double maxLat = latitude + radiusLat;
          
        Double mpdLng = degree*Math.cos(latitude * (PI/180));  
        Double dpmLng = 1 / mpdLng;  
        Double radiusLng = dpmLng*raidusMile;  
        Double minLng = longitude - radiusLng;  
        Double maxLng = longitude + radiusLng;  
        //System.out.println("["+minLat+","+minLng+","+maxLat+","+maxLng+"]");  
        return new double[]{minLat,minLng,maxLat,maxLng};
    }  
      
    /** 
     * 根据两点间经纬度坐标（double值），计算两点间距离，单位为米 
     * @param lng1 
     * @param lat1 
     * @param lng2 
     * @param lat2 
     * @return 
     */  
    public static double getDistance(double lng1, double lat1, double lng2, double lat2)  
    {  
       double radLat1 = lat1*RAD;  
       double radLat2 = lat2*RAD;  
       double a = radLat1 - radLat2;  
       double b = (lng1 - lng2)*RAD;  
       double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a/2),2) +  
        Math.cos(radLat1)*Math.cos(radLat2)*Math.pow(Math.sin(b/2),2)));  
       s = s * EARTH_RADIUS;  
//       s = Math.round(s * 10000) / 10000;  
       return s;  
    }  
      
    public static void main(String[] args){  
        Double lat1 = 34.264648;  
        Double lon1 = 108.952736;  
          
        int radius = 1000;  
        //[34.25566276027792,108.94186385411045,34.27363323972208,108.96360814588955]  
        getAround(lat1,lon1,radius);  
          
        //911717.0   34.264648,108.952736,39.904549,116.407288  
        double dis = getDistance(108.952736,34.264648,116.407288,39.904549);   
        System.out.println(dis);  
    }  
} 
